This applies to updating your Google Reader with new feeds replacing the old.

If you are using Google Reader and in the process of updating your subscriptions to include FilterMyRSS with keyword filter, be sure to only keep one window of Google Reader open.

For example, say you have one window open on GReader to copy the original RSS feed to FilterMyRSS for filtering; once the newly generated feed is made [with keyword filter] close the original Google Reader window before re-adding to your Google Reader list.

Why? This insures Google Reader updates properly with the new feed.